2.2.6 Literal constants

MIXAL allows the introduction of literal constants, which are
automatically stored in memory addresses after the end of the program by
the assembler. Literal constants are denoted as =wexp=, where
wexp is a w-expression (see W-expressions). For instance, the
code

L EQU 5
LDA =20-L=

causes the assembler to add after the program’s end an instruction
with contents 15 (‘20-L’), and to assemble the above code as the
instruction LDA a, where a stands for the address
in which the value 15 is stored. In other words, the compiled code is
equivalent to the following: